Power supply providing multiple output power to drive a plurality of electronic devices is a technique known in the art. The multiple output power can have differential potentials to supply electronic devices of different powers. Refer to FIG. 1 for a conventional power supply structure. It is connected to a power source 1 to receive input power. It mainly includes a power factor correction unit 2 to regulate the power factor of the input power, a transformer 3 connecting to the power factor correction unit 2 to receive the input power and generate an inductive power on a secondary side, and a switch circuit 4 electrically connected to the transformer 3 that has a switch 42 and a pulse width modulation unit 41 to drive the switch 42 ON or OFF. Through ON or OFF of the switch 42, the period of current passing through the transformer 3 can be altered, and the power transmitted from the primary side of the transformer 3 to the secondary side can be controlled. The inductive power of the secondary side of the transformer 3 is regulated by a plurality of output regulation units 51, 52 and 53 to become a plurality of output power delivered to corresponding output ends 61, 62 and 63. The output regulation units 51, 52 and 53 can deliver the output power at different potentials. The output regulation units 51, 52 and 53 are independent loops and cannot provide reciprocal compensation of the output power between them. Hence the conventional power supply provides power to an individual grounded load with an individual voltage. There is no energy compensation between two sets of voltages.